The survey showed Warren with a commanding nine-point lead over former Vice President Joe Biden and a 10-point lead over Sen. Bernie Sanders, I-Vt. Warren won the support of 29 percent of likely Democratic primary voters while Biden was the first choice of 20 percent and Sanders 19 percent, the newspaper reported. Sen. Kamala Harris, D-Calif., won the support of 8 percent of likely Democratic primary voters in her home state.

"We appear to be at an inflection point in the Democratic presidential campaign," Mark DiCamillo, the director of the poll, said. "The changing voting preferences of California Democrats may be a harbinger of things to come elsewhere across the country."

California, which moved its primary up to March 3 for the 2020 cycle, presents a treasure trove of delegates — the most of any state. The Berkeley poll surveyed 4,527 registered voters across the state, including 2,272 voters deemed likely to cast ballots in the Democratic primary and had a margin of error of 3 percentage points.

Elsewhere Wednesday, a Quinnipiac University poll found Warren to be leading the primary field with a two-point advantage over Biden nationwide, which is also within that poll's margin of error. Warren was the first choice of 27 percent of Democratic voters and Democratic-leaning independents while Biden won the support of 25 percent and Sanders 16 percent. While Biden saw much of his support come from older voters and Sanders from younger ones, Warren's support was about even across age groups.

That survey was the first time a candidate other than Biden led the Quinnipiac survey since it began asking voters for their preferences in March. Quinnipiac surveyed 561 Democratic voters and Democratic-leaning independents with a margin of error of 4.9 percentage points.